Valve for rock drills



April 20, 1954 s. D. GUNNING 2,675,784

. 7 VALVE FOR ROCK DRILLS Filed Jan. 2,. 1952 FIG.2

SAMUEL o euu'yme C ATTORNEY INVENTOR.

Patented Apr. 29, 1954 VALVE FOR ROCK DRILLS Samuel D. Gunning,Cleveland Heights, Ohio, assignor, by mcsne assignments, to Le RoiCompany, a corporation of Delaware Application January 2, 1952, SerialNo. 264,620

Claims.

This invention relates broadly to fluid actuated rock drills, but moreparticularly to a pressure fluid distributing automatic valve therefor.

One object of this invention is to produce a rock drill with aneflicient motive fluid distributing valve, which is simple inconstruction and readily responsive to the action of the pressure fluidthereon.

Another object of this invention is to produce a valve for a rock drillcapable of rapid and eificient distribution of the pressure fluidresulting in the fast and economical reciprocation of the rock drillpiston.

Another object of this invention is to produce a valve for rock drillswherein the pressure fluid supply to the piston chamber is measured bymeans other than the space between the valve and its associated seats,thereby enabling normal seat wear to take place without affecting thepressure fluid consumption of the drills.

Other objects of this invention will be apparent from the followingdetailed description wherein similar characters of reference designatecorresponding parts, and wherein:

Figure 1 is a longitudinal sectional view of a portion of a rock drillembodying the invention.

Figure 2 is a view similar to Figure 1, but showing some of the parts indiiierent positions.

Figure 3 is a partial cross-sectional view taken on line 33 in Figure 2and looking in the direction of the arrows.

Referring to the drawings, H) represents a cylinder formed with a pistonchamber I in which a piston I2 is capable of reciprocation. Piston l2has a stem l3 engageable with a drill steel, not shown, to deliverimpacts thereto, and is slidably guided in a front bushing or spacer l4.Intermediate its ends, the piston chamber H is provided with an exhaustgroove l5 which opens into an exhaust port H3.

The rear end of cylinder I0 is provided with a flat bottom counter-borell accommodating a valve cap l8 which rests against the bottom thereof,a valve chest I9 and a valve bushing 20, which together form a valvehousing having an annular valve 2| reciprocable therein. Also mounted inthe counterbore [1, there is the ratchet ring 22 of a rotation mechanismwhich includes the head 23 of a rifle bar 24 extending through the valvehousing into the piston l2 for imparting rotation thereto in the usualmanner. The valve cap, valve chest and bushing together with the ratchetring are held in the counterbore against relative rotation by a key ordowel pin, not shown, and against lengthwise movement by a bearing plate25 clamped against the ratchet ring by a back head 26 which ispreferably bolted to the cylinder 10.

The valve bushing 20 closes one end of the valve chest l9 and has acylindrical sleeve 27 surrounding the rifle stem 2e and near its freeend forming an internal sliding bearing 23 for the valve 2|. Externally,sleeve 21 is provided with an annular inlet groove 29 in constantcommunication with a supply chamber 30 through a system of ports 3|.

The valve 2| is formed with an external annular flange 32 slidablyengaging a corresponding inner wall of the chest I9 and having its sidesforming opposed actuating areas 33 and 34. The area 33 is in constantcommunication with the piston chamber through a kick port 35 which openstherein on one side of the exhaust groove [5, while a similar kick port36 opens in the piston chamber on the other side of the exhaust groovel5 and leads to the actuating area 34. Internally, the valve is formedof two different diameters, resulting in two internal portions, onesubstantially larger than the other, and united by a relatively Wideflat internal annular land 3'! having pressure fluid supplied theretothrough the bushing groove 29. From land 31, pressure fluid is conveyedto a front annular valve seat 42 provided on the cap I8 via equallyspaced ports 39 extending through the valve and opening in an annulargroove 38. This groove is cut in the end of the valve to provide twoannular and concentric radially spaced valve ends or sealing surfaces 49and 4| engageable with valve seat 42. From the front seat 42, pressurefluid may flow into the rear end of piston chamber through inlet ports43 controlled by the valve sealin surface 4| and through an enlargedinlet port or central bore 44 provided through valve cap I8 andcontrolled by valve sealing surface 49. Externally, the valve isslidably guided on the valve cap l8 as at 45 and in the chest I9 as at46. The other annular end or sealing surface 41 of the valve is of adiameter and area substantially equal to its end 4|, and is engageablewith a rear annular valve seat 48 formed on the valve bushing 29. Fromthe valve annular land 31, pressure fluid may flow through. an annularclearance or passageway 49 provided between valve bushing 20 and theinterior of the valve, over the end 41 of the valve into a relativelylarge annular groove 59, and therefrom to the front end of the pistonchamber I! through one or more inlet ports 5|. I

Rotatable Within the head 26, there is a throttle valve 52 formed with acentral inlet passage 53 and a radial port 54 capable of registrationwith a port 55 provided in the head 26 and Opening into supply chamber30.

In the operation of the tool, with the valve 2: and throttle valve 52positioned as shown in Fig. 1, pressure fluid such as compressed air issupplied to the throttle valve central inlet passage 53 from anysuitable source, such as an air compressor, and therefrom to the inletchamber 36 via ports 54 and 55. From inlet chamber 30, pressure fluid isfree to flow into inlet groove 29 through the system of ports 31, whichsystem includes spaces generally provided between the rifle bar head 25and its ring 22. From the valve internal annular land 31, which haspressure fluid supplied thereto through the groove 29, supply ofpressure fluid to the rear end of piston chamber H takes place throughthe valve ports 39, valve groove 38, over the valve sealing surfaces 46and M and through the inlet ports 43 and 44, while the supply ofpressure fluid to the front end of piston chamber II is shut off by thevalve end or sealing surface 41 engaging the valve rear seat 43.Pressure fluid thus admitted into the rear end of the piston chamberwill act on the piston 2 to drive it forwardly and deliver impact to thedrill steel. In this position of the valve, the unbalanced portion ofits opened end becomes a holding area subjected to the action of thepressure fluid for temporarily holding the valve on the rear seat 48. Asclearly shown in Figure 1, this unbalanced portion is limited to thearea of the annular end 4|, wln'ch is substantially equal to the area ofthe opposed end 41. As the piston i2 is driven forwardly, it willuncover the kick port 35 to admit pressure fluid on the valve actuatingarea 33 to shift the valve forwardly into engagement of its ends 49 and4| with the valve front seat 42, thereby shutting off the supply ofpressure fluid to the rear end of the piston chamber H. Immediatelybefore its impact on the drill steel, the piston 12 will also uncoverthe exhaust groove E5 to release the pressure fluid previously admittedinto the rear end of the piston chamber.

With the automatic valve positioned as shown in Fig. 2, pressure fluidfrom the valve annular land 31 is free to flow therefrom into the frontend of the piston chamber ll via the annular passageway 49, valve seat48, groove 5!] and ports 5?. In this instance, the area of the valve end4? together with the unbalanced area of the valve annular land 31, whichis equal to the area of the valve end 46, act as rear holding areas forholding the valve on the front seat 42. It will be understood that byproviding the valve front groove 36, the rear holding areas, whichotherwise would include the entire area of the land 31 less the combinedarea of the ports 39, are reduced to the area of valve end 41 and anarea equal to that of valve end 40. Pressure fluid in the front end ofpiston chamber II will effect the rearward stroke of the piston 12,causing it to uncover kick port 35 and admit pressure fluid to theactuating area 34 for shifting the valve to the position shown in Figure1; During its rearward stroke, piston I2 will also uncover exhaustgroove [5 to release the pressure fluid previously admitted in the frontend of chamber II.

In the present construction, the amount of pressure fluid supplied toboth ends of the piston chamber H is not controlled by the space betweenthe ends of the valve and their respective seats, but in one instance bythe size and number of ports 39 and in the other instance by the size ofthe annular passageway 49, thereby enabling the usual amount of seatwear to take place without affecting the pressure fluid consumption anddrilling characteristics of the tool. In other words, the volumetriccapacity of both valve openings is greater than that of the pressurefluid supplying means to the openings.

From the foregoing description, it will be understood that the automaticvalve 2| is provided on one end with two annular sealing surfaces 40 andll engageable with a common valve seat 42 for shutting off supply ofmotive fluid to the rear end of chamber ll, and on the other end withone sealing surface 47 for shutting off supply of motive fluid to thefront end of chamber I I.

It will also be understood that in order to assure proper engagement ofthe two valve sealing surfaces 40 and M with valve front seat 42, thevalve is provided with two holding areas, one formed on the end 4'! andthe other formed by the unbalanced portion of the annular land 31, whileproper engagement of the one valve sealing surface 41 with valve seat 48is assured by the one holding area 40.

It will also be further understood that details of structure andrearrangement of parts shown and described may be variously changed andmodified without departing from the spirit and scope of the invention.

I claim:

1. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve housing having opposed annular valve seats, an annularvalve reciprocable in said housing having its ends engageable with saidseats, inlet ports leading from said seats to said chamber, an internalannular land intermediate the ends of said valve having pressure fluidsupplied thereto, an annular passage way between an internal portion ofsaid valve and said housing to convey pressure fluid from said land toone of said seats, pressure fluid conveying ports through said valveleading from said land to the other of said seats, an external annularflange on said valve having opposed actuating areas intermittentlyexposed to pressure fluid controlled by said piston for actuating thevalve and causing intermittent engagement of its ends with said seats tocontrol supply of pressure fluid from said seats to said chamber viasaid inlet ports, and opposed holding areas on the ends of said valveintermittently exposed to pressure fluid from said seats for holding thevalve.

2. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve housing having opposed annular valve seats, an annularvalve reciprocable in said housin having ends of different areasengageable with said seats, inlet ports leading from said seats to saidchamber, an internal annular land intermediate the ends of said valvehaving pressure fluid supplied thereto, said valve being internallylarger on one side of said land than on the other to form with saidhousing an annular passageway to convey pressure fluid from said land toone of said seats, pressure fluid conveying ports through said valveleading from said land to the other of said seats, an external annularflange on said valve having opposed actuating areas intermittentlyexposed to pressure fluid controlled by said piston for actuating thevalve and causing intermittent engagement of its ends with said seats tocontrol supply of pressure fluid from said seats to said chamber viasaid inlet ports, and opposed holding surfaces on the ends of said valveof equal effective areas intermittently exposed to pressure fluid fromsaid seats for holding the valve.

3. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve housing having opposed annular valve seats, an annularvalve reciprocable in said housing, a sealing surface on on end thereofengageable with one of said seats and a duality of concentric radiallyspaced sealin surfaces on the other end thereof engageable with theother of said seats, inlet ports leading from said seats to saidchamber, an internal annular land intermediate the ends of said valvehaving pressure fluid supplied thereto, said valve bein internallylarger on one side of said land than on the other to form with saidhousing a pressure fluid conveying annular passageway leading from saidland to one of said seats, pressure fluid conveying ports through saidvalve leading from said land to the other of said seats and openingbetween said concentric sealin surfaces, an external annular flange onsaid valve having opposed actuating areas intermittently exposed topressure fluid controlled by said piston for actuating the valve andcausing intermittent engagement of said sealing surfaces with theirrespective seats to control supply of pressur fluid from said seats tosaid chamber via said inlet ports, and opposed means on said valveintermittently exposed to pressure fluid for holding said valve on oneor the other of said seats, said means including a holdin area forholding said valve on one of said seats and a duality of holding areasincluding a portion of said annular land for holding said valve on theother seat.

4. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve housing having opposed annular valve seats, an annularvalve reciprocable in said housing having its ends engageable with saidseats, inlet ports leading from said seats to said chamher, an internalannular land intermediat the ends of said valve having pressure fluidsupplied thereto, an annular clearance between the interior of saidvalve and said housing to convey pressure fluid from said land to one ofsaid seats, pressure fluid conveying ports through said valve leadinfrom said land to the other of said seats, an external annular flang onsaid valve having opposed actuating areas intermittently exposed topressure fluid controlled by said piston for actuating the valve andcausing intermittent engagement of its ends with said seats to controlsupply of pressure fluid from said seats to said chamber via said inletports, the amount of pressure fluid supplied to said chamber beinggoverned by the volumetric capacity of said clearance and pressure fluidconveying ports, and opposed holding areas on the ends of said valveintermittently exposed to pressure fluid from said seats for holdin thevalve.

5. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve housing having opposed front and rear annular valveseats, an annular valve reciprocabl in said housing having its endsengageable with said seats, inlet ports leading from said seats to saidchamber, said valve havin two internal portions of different diametersforming at their junction an internal annular land, means including asystem of ports through said housing supplying pressure fluid to saidland, an annular passageway between one of said portions and saidhousing conveying pressure fluid from said land to said rear seat,pressure fluid conveying ports through said valve leading from said landto said front seat, an external annular flange on said valve havingopposed actuating areas intermittently exposed to pressure fluidcontrolled by said piston for actuating the valve and causingintermittent engagement of its ends with said seats to control supply ofpressure fluid from said seats to said chamber via said inlet ports, andopposed holding areas on the ends of said valve intermittently exposedto pressure fluid from said seats for holding said valve.

References Cited in the flle of this patent UNITED STATES PATENTS NumberName Date 2,048,957 Smith, S12, et a1. July 28, 1936 2,448,875 FossumSept. '7, 1948

